U.S. patent number 8,778,083 [Application Number 12/841,139] was granted by the patent office on 2014-07-15 for lateral-flow deposition apparatus and method of depositing film by using the apparatus.
This patent grant is currently assigned to ASM Genitech Korea Ltd.. The grantee listed for this patent is Seung Woo Choi, Dong Rak Jung, Jung Soo Kim, Ki Jong Kim, Jeong Ho Lee, Hyung Sang Park, Yong Min Yoo. Invention is credited to Seung Woo Choi, Dong Rak Jung, Jung Soo Kim, Ki Jong Kim, Jeong Ho Lee, Hyung Sang Park, Yong Min Yoo.
United States Patent |
8,778,083 |
Kim , et al. |
July 15, 2014 |
Lateral-flow deposition apparatus and method of depositing film by
using the apparatus
Abstract
A deposition apparatus according to an exemplary embodiment of
the present invention is a lateral-flow deposition apparatus in
which in which a process gas flows between a surface where a
substrate is disposed and the opposite surface, substantially in
parallel with the substrate. The lateral-flow deposition apparatus
includes: a substrate support that moves up/down and rotates the
substrate while supporting the substrate; a reactor cover that
defines a reaction chamber by contacting the substrate support; and
a substrate support lifter and a substrate support rotator that
move the substrate support.
Inventors: |
Kim; Ki Jong (Daejeon-si,
KR), Yoo; Yong Min (Cheonan-si, KR), Kim;
Jung Soo (Cheonan-si, KR), Park; Hyung Sang
(Seoul, KR), Choi; Seung Woo (Cheonan-si,
KR), Lee; Jeong Ho (Seoul, KR), Jung; Dong
Rak (Cheonan-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Kim; Ki Jong
Yoo; Yong Min
Kim; Jung Soo
Park; Hyung Sang
Choi; Seung Woo
Lee; Jeong Ho
Jung; Dong Rak |
Daejeon-si
Cheonan-si
Cheonan-si
Seoul
Cheonan-si
Seoul
Cheonan-si |
N/A
N/A
N/A
N/A
N/A
N/A
N/A |
KR
KR
KR
KR
KR
KR
KR |
|
|
Assignee: |
ASM Genitech Korea Ltd.
(Cheonan-Si, KR)
|
Family
ID: |
43497546 |
Appl.
No.: |
12/841,139 |
Filed: |
July 21, 2010 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
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US 20110020545 A1 |
Jan 27, 2011 |
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Foreign Application Priority Data
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|
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Jul 22, 2009 [KR] |
|
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10-2009-0067047 |
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Current U.S.
Class: |
118/730; 118/725;
118/724; 118/733 |
Current CPC
Class: |
C23C
16/466 (20130101); C23C 16/45504 (20130101); C23C
16/4584 (20130101); C23C 16/45544 (20130101) |
Current International
Class: |
C23C
16/00 (20060101) |
Field of
Search: |
;156/914,345.51-345.55
;118/725,728-731,733 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
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10-0273473 |
|
Sep 2000 |
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KR |
|
10-0624030 |
|
Sep 2006 |
|
KR |
|
10-2008-0005970 |
|
Jan 2008 |
|
KR |
|
Primary Examiner: Baldwin; Gordon R
Assistant Examiner: Bennett; Charlee
Attorney, Agent or Firm: Lexyoume IP Meister, PLLC
Claims
What is claimed is:
1. A lateral-flow deposition apparatus in which a process gas flows
between a first surface of a reaction chamber where a substrate is
disposed and a second surface of the reaction chamber facing the
first surface, the process gas flowing in a direction that is
substantially in parallel with the substrate, the apparatus
comprising: a substrate support that moves up/down and rotates the
substrate while supporting the substrate; a substrate support
heater disposed under the substrate support, transferring heat to
the substrate support, and moving up/down, wherein the substrate
support heater and the substrate support are spaced at a distance
from each other; a reactor cover that defines the reaction chamber
by contacting the substrate support heater; a substrate support
lifter and a substrate support rotator that move the substrate
support; and a sub-gas inlet allowing a sub-gas to be injected
between the substrate support and the substrate support heater,
wherein the sub-gas inlet is disposed at a center portion of the
substrate support heater.
2. The apparatus of claim 1, wherein: heat of the substrate support
heater is transferred to the substrate support by the sub-gas.
3. The apparatus of claim 1, wherein: the sub-gas flows to prevent
the process gas from flowing under the substrate support.
4. The apparatus of claim 1, further comprising: a substrate
support pin supporting the substrate independently from the
substrate support and moving up/down; and a support pin driver
moving up/down the substrate support pin.
5. The apparatus of claim 4, further comprising: a support pin base
connecting the support pin driver with the substrate support
pin.
6. The apparatus of claim 1, wherein: the substrate support rotator
rotates the substrate support while the process gas flows on the
substrate in the defined reaction chamber without opening the
reaction chamber, preventing foreign substances from flowing into
the reaction chamber during the rotation of the substrate
support.
7. The apparatus of claim 1, wherein: the substrate support rotator
rotates the substrate support by n.degree., and the rotation of the
substrate support is performed at least (360.degree./n.degree.)
times.
8. The apparatus of claim 1, wherein: the substrate support is
rotated by the substrate support rotator in the defined reaction
chamber while the reactor cover contacts the substrate support
heater.
9. The apparatus of claim 7, wherein: a flow rate of the process
gas is controlled according to the rotation of the substrate.
10. The apparatus of claim 7, wherein: a concentration of the
process gas is controlled according to the rotation of the
substrate.
11. The apparatus of claim 7, wherein: a flow direction of the
process gas is changed with respect to a center of the substrate by
the rotation of the substrate support.
12. The apparatus of claim 7, wherein: a thickness of a thin film
deposited on the substrate increases by a predetermined thickness
every time when the substrate support is rotated during deposition
of the thin film on the substrate.
13. The apparatus of claim 1, wherein: the sub-gas inlet is
disposed around the substrate support lifter.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority to and the benefit of Korean
Patent Application No. 10-2009-0067047 filed in the Korean
Intellectual Property Office on Jul. 22, 2009, the entire contents
of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a lateral-flow deposition
apparatus and a method of depositing film by using the
apparatus.
(b) Description of the Related Art
A study for improving processes of apparatuses forming a
high-quality film on a substrate in manufacturing semiconductor
device has been conducted. Recently, an atomic layer deposition
(ALD) has been proposed, which enables to form a thin film on a
substrate by using surface reaction of two or more reaction gases
that are sequentially supplied on a substrate at different time,
and forms a thin film having a desired thickness by repeating this
sequence. Since the film is formed by the surface reaction,
according to this process, it is possible to achieve a film having
a uniform thickness throughout the surface of the substrate,
regardless of protrusions and depressions of the substrate, and
form a film having excellent properties by reducing impurities
contained in the film.
According to the atomic layer deposition, reaction gasses are
sequentially supplied into a reactor in the order of a first
reaction gas.fwdarw.an inert purge gas.fwdarw.a second reaction
gas.fwdarw.an inert purge such that the reaction gases do not meet
or react in a gas state in a reaction chamber, by using respective
valves for each gas. This sequence is called `cycle`. Some of the
reaction gases may be activated by plasma. Plasma atomic layer
deposition that intermittently provides plasma in a reactor in
synchronization with the sequential gas supply cycle has been
disclosed in Korea Patent No. 273473 and U.S. Pat. No.
6,645,574.
In the atomic layer deposition apparatus used for atomic layer
deposition, the gases flow fast and simply in parallel with a
substrate in the reactor, so the lateral-flow atomic layer
deposition reactor can lead to fast gas switching and minimize time
for supplying sequentially the gases in a cycle As an example of
the lateral-flow reactor, a reactor suitable for time-division gas
supply atomic deposition and a method of depositing a thin film in
the reactor has been disclosed in Korea Patent No. 624030 and U.S.
Pat. No. 6,539,891. Further, a modified example has been disclosed
in Korea Patent Application No. 2005-0038606 and U.S. patent
application Ser. No. 11/429,533. According to this reactor, it is
possible to perform plasma atomic layer deposition by supplying
plasma power to an electrode, which supplies radio frequency (RF)
power, in synchronization with the gas supply cycle.
Other examples of the lateral-flow atomic layer reactor have been
disclosed in U.S. Pat. No. 5,711,811 and U.S. Pat. No. 6,562,140.
In these inventions, the gas flow is maintained uniformly and close
to laminar flow on a substrate by maintaining the gap between a
surface where the substrate is placed and the surface opposite to
the substrate in the reactors.
It is possible to form a completely uniform film, if atomic layers
are formed layer by layer on the substrate; however, practically,
non-uniformity of about 3% usually exists in the film formed by the
atomic layer deposition, because of various reasons, particularly,
because it is required to increase the deposition rate and
productivity of the equipment by reducing the time for supplying
gases in a cycle.
When the lateral-flow deposition reactor is used, the
non-uniformity is generated usually in the gas flow direction.
Further, the thickness of a thin film deposited in the lateral-flow
deposition apparatus is larger usually at the gas inlet than the
gas outlet, because the concentration of the gas is generally high
at the gas inlet than at the gas outlet.
The above information disclosed in this Background section is only
for enhancement of understanding of the background of the invention
and therefore it may contain information that does not form the
prior art that is already known in this country to a person of
ordinary skill in the art.
SUMMARY OF THE INVENTION
The present invention has been made in an effort to provide a
lateral-flow deposition apparatus and a lateral-flow deposition
method having advantages of improving uniformity of a thin film
formed on a substrate.
An exemplary embodiment of the present invention provides a
deposition apparatus, which is a lateral-flow deposition apparatus
in which a process gas flows between a surface where a substrate is
disposed and the opposite surface, substantially in parallel with
the substrate. The lateral-flow deposition apparatus includes: a
substrate support that moves up/down and rotates the substrate
while supporting the substrate; a reactor cover that defines a
reaction chamber by contacting the substrate support; and a
substrate support lifter and a substrate support rotator that move
the substrate support.
The lateral-flow deposition apparatus may further includes a
substrate support heater disposed under the substrate support,
transferring heat to the substrate support, and moving up/down.
The substrate support heater and the substrate support may be
spaced at a distance from each other.
The lateral-flow deposition apparatus may further include a sub-gas
inlet allowing a sub-gas to be injected between the substrate
support and the substrate support heater.
Heat of the substrate support heater may be transferred to the
substrate support by the sub-gas.
The sub-gas may flow to prevent the process gas from flowing under
the substrate support.
The lateral-flow deposition apparatus may further include: a
substrate support pin supporting the substrate independently from
the substrate support and moving up/down; and a support pin driver
moving up/down the substrate support pin.
The lateral-flow deposition apparatus may further include a support
pin base connecting the support pin driver with the support
pin.
The substrate support rotator may rotate the substrate support
while the process gas flows on the substrate.
The substrate support rotator may rotate the substrate support by
n.degree., and the rotation of the substrate support is performed
at least)(360.degree./n.degree.) time.
The reactor cover may define a reaction chamber by contacting the
substrate support, when the substrate support rotates.
Another embodiment of the present invention provides a method of
lateral-flow deposition in which a process gas flows between a
surface where a substrate is placed and the opposite surface
substantially in parallel with the substrate. The method includes:
depositing a portion of a desired thickness on the substrate by
supplying a process gas in a predetermined direction; changing the
flow direction of the process gas with respect to the center of the
substrate by rotating the substrate with a portion of the desired
thickness deposited; and depositing a portion of the desired
thickness on the substrate where the process gas flow is changed,
in which the rotation of the substrate is performed with the
reaction space in which the process gas flows defined on the
substrate.
A portion of the desired thickness may be 1/m (m is a natural
number of 2 or more) of the desired thickness.
The substrate may be rotated by about 360/m.degree. relatively to
the flow direction of the process gas.
The substrate may be repeatedly rotated at least m times.
According to a lateral-flow deposition apparatus and a method
thereof of an exemplary embodiment of the present invention, the
substrate is rotated during the thin film deposition process, the
flow direction of the process gas is changed with respect to the
center of the substrate by rotating the substrate on which a
portion of a desired thickness is deposited. Accordingly, it is
possible to achieve a thin film having improved uniformity by
repeating this work. Further, it is possible to simply and rapidly
rotate the substrate and deposit a thin film, as compared with
deposition apparatuses that separately perform a film deposition
process and a substrate rotation process, thereby reducing the
entire process time, by rotating the substrate in the deposition
process. Further, since the substrate is rotated with the reaction
chamber blocked from the outside, it is possible to prevent foreign
substances from flowing into the reaction chamber, as compared with
deposition apparatuses that separately perform a film deposition
process and a substrate rotation process, thereby improving the
quality of the deposited thin film.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view schematically showing a
lateral-flow atomic layer deposition apparatus according to an
exemplary embodiment of the present invention;
FIG. 2A to FIG. 2J are cross-sectional views sequentially showing a
deposition apparatus according to an exemplary embodiment of the
present invention, before and after a deposition process; and
FIG. 3A to FIG. 3E are schematic views showing gas flow with
respect to positions on the surface of a substrate provided in a
deposition apparatus according to an exemplary embodiment of the
present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
The present invention will be described more fully hereinafter with
reference to the accompanying drawings, in which exemplary
embodiments of the invention are shown. As those skilled in the art
would realize, the described embodiments may be modified in various
different ways, all without departing from the spirit or scope of
the present invention.
In the drawings, the thickness of layers, films, panels, regions,
etc., are exaggerated for clarity. Like reference numerals
designate like elements throughout the specification. It will be
understood that when an element such as a layer, film, region, or
substrate is referred to as being "on" another element, it can be
directly on the other element or intervening elements may also be
present. In contrast, when an element is referred to as being
"directly on" another element, there are no intervening elements
present.
Hereinafter, a lateral-flow deposition apparatus according to an
exemplary embodiment of the present invention is described with
reference to FIG. 1. FIG. 1 is a cross-sectional view schematically
showing a lateral-flow atomic layer deposition apparatus according
to an exemplary embodiment of the present invention.
Referring to FIG. 1, a deposition apparatus 100 according to an
exemplary embodiment of the present invention includes a substrate
support 101 rotatably supporting a substrate 210, a substrate
support heater 102 heating the substrate support 101, a substrate
support pin 103, sub-gas inlet 106, a substrate support driver 110,
a substrate support pin driver 120, a substrate support heater
lifter 130, and a reactor cover 140 defining a reaction chamber by
contacting the substrate support heater 102. Further, the
deposition apparatus 100 according to an exemplary embodiment of
the present invention further include gas flow channels 311, 312
connected with the reactor cover 140 and allows a process gas to
flow inside and moving inside the reaction chamber, and a gas
discharge channel 320 for discharging the gas. Further, the
deposition apparatus 100 further includes a sub-gas inflow channel
321 allowing a sub-gas flowing inside through the sub-gas inlet 106
to flow into the reaction chamber and a sub-gas flow channel 322
allowing the sub-gas flowing in the reaction chamber to move inside
the reaction chamber. The flow direction of each gas is indicated
by arrows in FIG. 1.
The substrate support driver 110 includes a substrate support
lifter 107 moving up/down the substrate support 101, a substrate
support rotator 108 rotating the substrate support 101, and a
rotational reference plate 109 defining the reference position of
the substrate support 101.
The substrate support pin driver 120 includes a support pin base
104 for moving up/down the substrate support pin 103 and a support
pin lifter 105 connected with the support pin base 104.
Structures 151, 152 inducing gas flow are disposed in the reaction
chamber in order to allow the gas to flow on and in parallel with
the substrate and maintain the gas flow in substantially laminar
flow in the reaction chamber. The position `x` corresponds to the
inflow portion of the lateral-flow gas and the position `y`
corresponds to the outflow portion of the lateral-flow gas, on the
substrate 210.
Hereinafter, the operation of the deposition apparatus 100
according to an exemplary embodiment of the present invention is
described with reference to FIG. 2A to FIG. 2J. FIG. 2A to FIG. 2J
are cross-sectional views sequentially showing a deposition
apparatus according to an exemplary embodiment of the present
invention, before and after a deposition process.
Before a deposition process, as shown in FIG. 2A, the substrate
support 101, the substrate support heater 102, and the substrate
support pin 103 are down with the reaction chamber open by the
substrate support lifter 107, the substrate support heater lifter
130, and the support pin lifter 105, and the substrate 210 is
mounted on a substrate transfer 400, such as a robot arm, which is
disposed outside the reactor, and inserted in the reactor.
Thereafter, as shown in FIG. 2B, as the support pin lifter 105
moves up the support pin base 104, the substrate support pin 103
moves up to support the substrate 210 on the substrate transfer
400, and as shown in FIG. 2C, the substrate transfer 400 moves
outside of the reactor while the substrate support pin 103 supports
the substrate 210.
Next, as shown in FIG. 2D, as the support pin lifter 105 moves
downs, the support pin base 104 moves down, and the substrate
support pin 103 and the substrate 210 move down, such that the
substrate 210 is placed on the substrate support 101. A shown in
the figures, the substrate support 101 of the deposition apparatus
according to an exemplary embodiment of the present invention is
disposed at a predetermined distance from the substrate support
heater 102.
Next, as shown in FIG. 2E, the substrate support 101 and the
substrate support heart 102 are moved up to define the reaction
chamber by the substrate support lifter 107 and the substrate
support heater lifter 130, and the substrate support heater 102
heats the substrate support 101 and the substrate 210 up to desired
temperature. In this operation, sub-gas flows inside through the
sub-gas inlet 106, and continues flowing to the substrate support
101 and the substrate support heater 102 through the sub-gas inflow
channel 321 and the sub-gas flow channel 322. The sub-gas is an
inert gas. The sub-gas functions as a heat transfer medium between
the substrate support heater 102 and the substrate support 101,
which are spaced apart from each other, and in detail, the sub-gas
is heated by the substrate support heater 102 and flows under the
substrate support 101 such that the heat is more efficiently
transferred from the spaced substrate support heater 102 to the
substrate support 101.
Next, as shown in FIG. 2F, a process gas flows inside and continues
flowing on the substrate 210 through the process gas flow channels
311, 312 and the sub-gas flows inside through the sub-gas inlet 106
and continues flowing between the substrate support 101 and the
substrate support heater 102 through the sub-gas inflow channel 321
and the sub-gas flow channel 322, such that a thin film is
deposited on the substrate 210 by reaction of the process gas. In
the process, the process gas flows from the gas inlet portion `x`
to the gas outlet portion `y` on the substrate 210 substantially in
parallel with the surface of the substrate 210, while maintaining
substantially laminar flow. Since the sub-gas flows under the
substrate support 101 to the reactor, the process gas flowing
through the process gas flow channel 311, 312 is prevented from
flowing under the substrate support 101, such that it is possible
to prevent a thin film from being deposited at undesired positions,
such as the rear side of the substrate 210 or the rear side of the
substrate support 101.
As shown in FIG. 2G, while the process gas flows inside and a thin
film is deposited on the substrate 210, the substrate support 101
is rotated by the substrate support rotator 108 and the substrate
210 on the substrate support 101 is correspondingly rotated, such
that the gas inflow portion `x` is arranged to the gas outlet and
the gas outflow portion `y` is arranged to the gas inlet.
Therefore, it is possible to reduce changes in flow rate or
concentration of the process gas depending on the positions on the
substrate 210, such that it is possible to improve uniformity of
the thin film deposited on the substrate 210.
Although the present exemplary embodiment exemplifies when the
substrate is rotated about at 180.degree. by the rotation of the
substrate support 101, the rotation of the substrate support 101
can by controlled to desired angles and the number of rotation can
also be controlled to desired levels. For example, when the
substrate support 101 rotates n.degree., the number of rotation may
be 360.degree./n.degree. and the substrate 210 may rotate
360.degree. in a horizontal plane in the step of rotation.
Accordingly, the average direction of the flow of the process gas
can be substantially uniform about the center of the substrate,
throughout the substrate. It is possible to determine whether the
substrate 210 finishes rotating 360.degree. by determining the
reference position of the rotational reference plate 109.
As described above, according to the deposition apparatus 100 of an
exemplary embodiment of the present invention, during a process of
thin film deposition, a portion of desired thickness is deposited
on the substrate by supplying a reaction gas in a predetermined
direction, the flow direction of the process gas is changed with
respect to the center of the substrate by rotating the substrate
support 101 and the substrate 210 deposited with a portion of the
desired thickness in the lateral-flow deposition apparatus 100, and
then a portion of desired thickness is deposited on the substrate
on which the flow direction of the gas is changed. Accordingly, it
is possible to achieve a thin film having improved uniformity by
repeating this work. Further, it is possible to simply and quickly
rotate the substrate and deposit the thin film by rotating the
substrate 210 during the deposition process, as compared with
deposition apparatuses that separately perform a film deposition
process and a substrate rotation process, thereby reducing the
entire process time. Further, since the substrate is rotated in the
reaction chamber defined, it is possible to prevent foreign
substances from flowing into the reaction chamber, as compared with
deposition apparatuses that separately perform a film deposition
process and a substrate rotation process, so reaction chamber is
opened to rotate substrate. This invention, however, enables to
rotate substrate without opening the reaction chamber, and
preventing foreign substances from flowing into reactor, thereby
improving the quality of the deposited thin film.
By these processes, after a thin film having a desired thickness is
formed on the substrate 210, as shown in FIG. 2H, the substrate
support 101 and the substrate support heater 102 are moved down by
the substrate support lifter 107 and the substrate support heater
lifter 130 to open the reaction chamber, and the substrate 210 is
placed on the substrate support pin 103.
Thereafter, as shown in FIG. 2I, the substrate transfer 400 is
moved into the open reaction chamber, as shown in FIG. 2J, the
substrate support pin 103 is moved down by the support pin lifter
105 and the substrate 210 is placed on the substrate transfer 400,
and the substrate transfer 400 is taken out of the reaction chamber
and the substrate 210 that has undergone the deposition process is
taken out of the reactor.
Hereafter, a deposition method using the deposition apparatus 100
according to an exemplary embodiment of the present invention is
described with reference to FIG. 3A to FIG. 3D. FIG. 3A to FIG. 3D
are schematic views showing gas flow with respect to positions on
the surface of a substrate provided in a deposition apparatus
according to an exemplary embodiment of the present invention.
Referring to FIG. 3A, the position A corresponds to the process gas
inflow portion and the position C corresponds to the process gas
outflow portion in the substrate, in the initial state of the thin
film deposition process. Therefore, the flow rate or concentration
of the process gas is the highest at the position A and the lowest
at the position C of the substrate, and the concentration is the
middle at the position B and D in the substrate. A portion of a
thin film is deposited and the substrate is rotated, at the initial
concentration of the process gas. The present exemplary embodiment
exemplifies when the substrate rotates at about 90.degree. for each
time. Therefore, the total rotation number is at least
(360.degree./90.degree.=) 4 times. Further, the thickness of the
thin film deposited on the substrate for each rotation may be m/4
of the desired thickness (m).
Referring to FIG. 3B, when the substrate is rotated one time, the
position D corresponds to the process gas inflow portion and the
position B corresponds to the process gas outflow portion in the
substrate. Therefore, the flow rate or concentration of the process
gas is the highest at the position D, the lowest at the position B
of the substrate, and the middle at the positions A and C in the
substrate. A portion (m/4 of the desired thickness `m`) of the thin
film is deposited and the substrate is rotated at the initial flow
rate and concentration of the process gas.
Referring to FIG. 3C, when the substrate is rotated twice, the
position C corresponds to the process gas inflow portion and the
position A corresponds to the process gas outflow portion in the
substrate. Therefore, the flow rate or concentration of the process
gas is the highest at the position C, the lowest at the position A,
and the middle at the positions D and B in the substrate. A portion
(m/4 of the desired thickness `m`) of the thin film is deposited
and the substrate is rotated at the initial flow rate and
concentration of the process gas.
Referring to FIG. 3D, when the substrate is rotated three times,
the position B corresponds to the process gas inflow portion and
the position D corresponds to the process gas outflow portion in
the substrate. Therefore, the flow rate or concentration of the
process gas is the highest as the position B, the lowest at the
position D, and the middle at the positions C and A in the
substrate. A portion (m/4 of the desired thickness `m`) of the thin
film is deposited and the substrate is rotated at the initial flow
rate and concentration of the process gas.
Referring to FIG. 3E, when the substrate is rotated four times, as
in the initial state of the thin film deposition process, the
position A corresponds to the process gas inflow portion and the
position C corresponds to the process gas outflow portion in the
substrate.
It is possible to reduce the difference in flow rate or
concentration of the process gas depending on the positions on the
substrate by repeating these works, such that it is possible to
achieve a thin film having a desired thickness `m` and improved
uniformity.
While this invention has been described in connection with what is
presently considered to be practical exemplary embodiments, it is
to be understood that the invention is not limited to the disclosed
embodiments, but, on the contrary, is intended to cover various
modifications and equivalent arrangements included within the
spirit and scope of the appended claims.
* * * * *